Filter cartridge construction

ABSTRACT

A filtration module ( 10 ) is provided which includes a manifold ( 12 ), a filter cartridge ( 16 ) and a bowl ( 14 ) which houses the filter cartridge ( 16 ). The filter cartridge ( 16 ) and bowl ( 14 ) are connected to each other by a key ( 30 ) which is secured to flat surfaces ( 38 ) on the cartridge ( 16 ) to form a unitary construction. The filter cartridge ( 16 ) and bowl ( 14 ) are in fluid communication with the manifold ( 12 ) in a manner which prevents mixing of a fluid feed to the module ( 10 ) and a permeate removed from the module ( 10 ).

BACKGROUND OF THE INVENTION

The present invention relates to membrane filtration modules and afiltration cartridge that are more sanitary and are easier to replaceand install than presently available filtration modules. Moreparticularly, the present invention relates to a filtration cartridgeand membrane filtration modules formed from a filtration cartridge, areusable bowl, a reusable manifold and a reusable connecting device toconnect the filtration cartridge, retaining bowl and manifold together.

The control of particulate contaminants in a filtration process such asin the semiconductor industry requires the use of ultraclean filtershaving membranes that remove submicron particles. It is well known thatany particle that is deposited on a semiconductor wafer produces adefect when the particle is sufficiently large. Typically, in thesemiconductor industry, failed defects can be produced by particles assmall as about one tenth of the smallest features of the semiconductorchip. Therefore, membrane filters are used in every process step forproducing semiconductor chips to purify both working liquids and gases.

Although many different designs have been developed for a filtrationmodule used in an ultrapure liquid filtration, two designs areprevalent. In one module design, liquid to be filtered flows from oneend of the filtration module to the other end. In this class offiltration modules, the feed and permeate connections are located atopposite ends of the filter thereby forcing the liquid flow to move fromone end to the other. This flow configuration is referred to as an inline flow configuration. These filtration modules suffer from twodisadvantages. First, they are more difficult to connect to the processequipment since the module is sandwiched between two sets ofconnections. Second, any free liquid remaining within the module quicklydrains upon disconnection of the module because at least one connectionis positioned at the bottom of the module.

A second filtration modular design locates all of the connections at thesame end of the module. In this type of module, the feed and permeateports are typically horizontally oriented at the top of “head” end ofthe module on opposite sides thereof. Due to their shape, these modulesare referred to as having a T configuration. The T configurationfacilitates connection of the head to the remaining portion of thefiltration module comprising the bowl and the filtration cartridgepositioned within the bowl. In this design, the bowl and filtrationcartridge comprise separate elements. Thus, when constructing thefiltration module, the filtration cartridge and the bowl are separatelysecured to and sealed to the manifold head. In addition, upon completionof filtration, the bowl and cartridge are separately removed from thehead. This separate removal requires that the bowl be moved a distancesubstantially greater than the entire length of the cartridge therebyexposing the cartridge to permit its removal. Thereafter, the exposedcartridge is removed by hand or with a hand tool. Since the filtercartridge is saturated with the liquid being filtered which is oftentimes corrosive or toxic, the cartridge removal step presents a dangerto the worker. In addition, since the bowl must be moved the length ofthe cartridge, the space within which the bowl and cartridge arepositioned must accommodate this removal step.

It has been proposed in U.S. Pat. No. 5,114,572, to provide a filterassembly which cooperates with a bowl to produce a filter cartridge-bowlconstruction which can be demounted as a single unit from a manifold.The filter cartridge is connected to the bowl by bayonet connections onthe cartridge which fit into grooves within the interior surface of thebowl. The bayonet connections are formed integrally with the cartridgesuch as by being molded as a single unit. When the cartridge isso-configured, it can only be used with a bowl configured to accept thebayonet. This is undesirable since it prevents the so-configuredcartridge to be used with presently produced bowls configured to notaccept this cartridge. This, in turn, severely reduces the market forthe so-configured cartridge. In addition, the bayonet connections arepositioned below the top surface of the cartridge so that they fit intogrooves in the bowl also positioned below the top surface of thecartridge. When the bayonets are so-positioned, positioning in thegrooves is made more difficult by the reduced visibility.

Accordingly, it would be desirable to provide a filtration cartridgewhich permits its use in a plurality of bowls of differentconfigurations. In addition, it would be desirable to provide such acartridge which includes a connection means between the cartridge and abowl with means that are not movable relative to the cartridge duringfiltration. In addition, it would be desirable to provide such acartridge having a connection means which are clearly visible so thatconnection of the cartridge to the bowl is facilitated. Such a cartridgewould promote ease of inserting the filter cartridge into the bowl,would eliminate the danger to the worker in removing the filtercartridge subsequent to filtration and would reduce the space requiredto install the filtration module.

SUMMARY OF THE INVENTION

In accordance with this invention, a filtration module is providedcomprising a manifold, and the combination of a filter cartridge andbowl wherein the filter cartridge and bowl are locked together to beinstalled and removed as one piece from the manifold. The filtercartridge includes a fluid passageway for fluid communication betweenthe manifold and the interior of the cartridge. The outside surface ofthe fluid passageway includes two flat parallel surfaces which mate withtwo flat surfaces of a key so that the key can be slideably mounted onthe fluid passageway. In a first embodiment, the key is provided withbayonets which fit into slots in the bowl thereby to effect connectionsof the cartridge to the bowl. In a second embodiment, the key isprovided with hook-shaped elements which are snap fit over the open lipof the bowl thereby to effect connection of the cartridge to the bowl.The key is removable form the filter cartridge so that the cartridge canbe utilized with a conventional bowl not secured to the filter cartridgeor with the bowl utilized in the filter module of this invention. Thekey and bayonets or the key and hook-shaped elements which secure thecartridge to the bowl permit the cartridge and bowl to be removed as onepiece from the manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a filter module of this invention.

FIG. 2 is an isometric view of a cartridge top and mating key of thisinvention.

FIG. 3 is an isometric view of a collar used in conjunction with thecartridge and key of FIG. 2.

FIG. 4 is an isometric view illustrating a bowl and collar of thisinvention.

FIG. 5 is an isometric view illustrating a key and tool for installingthe cartridge into a bowl.

FIG. 6 is an isometric view of a means for transporting and installing acartridge without touching the cartridge.

FIG. 7 is a top isometric view of an alternative key construction ofthis invention.

FIG. 8 is a cross sectional view of the key of FIG. 7, directlypositioned on a bowl.

FIG. 9 is a bottom perspective view of an alternate key of thisinvention.

FIG. 10 is a partial cross sectional view of the position of the key ofFIG. 9 on the collar shown in FIG. 11.

FIG. 11 is a perspective view of a collar having slots to accommodatethe key of FIG. 9.

FIG. 12 is a top perspective view of an alternate key of this invention.

FIG. 13 is a perspective view of the key of FIG. 12 fitting with thecollar of FIG. 11.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention provides a filter cartridge and a filtrationmodule formed of a manifold, the filtration cartridge and a bowl. Themanifold provides fluid pathways for fluid feed into the filtrationcartridge and permeate removal from the filtration cartridge. The bowlprovides a means of storing fluid feed to permit its introduction intothe filtration cartridge or to store permeate from the filtrationcartridge to be directed to the manifold and then from the filtrationmodule. Fluid feed can be introduced into the filtration cartridgethrough the manifold either from the outside of the filter cartridge orfrom within the interior of the filtration cartridge. The fluid in thebowl adjacent the filtration cartridge can be either fluid feed orpermeate. In any event, the fluid feed is introduced from a manifoldinto the filtration cartridge, permeate is removed from the filtrationcartridge from the manifold and sealing is provided to prevent admixtureof fluid feed and permeate.

The filtration cartridge and bowl are constructed so that they aresealed with the manifold or removed from contact with the manifold asone piece. The filter cartridge is sealed with two end caps, one ofwhich is provided with a fluid passageway. The fluid passageway has twoopposing substantially parallel flat surfaces positioned on its outsidesurface. The cartridge is provided with a key that is slideably mountedon the two flat surfaces thereby to be positioned around the fluidpassageway of the cartridge. The fluid passageway can function as aninlet or outlet of the cartridge. The key is configured to effectlocking of the cartridge to the bowl. In one embodiment, the bowl andfilter cartridge are joined together by bayonets on the key which fitinto slots on the interior surface of the bowl. In a second embodiment,the key is joined to the bowl by being snap fit onto the open top lip ofthe bowl. The flat surfaces on the fluid passageway prevent the key fromrotating relative to the cartridge. Subsequent to a filtration, the bowland filter cartridge are removed from the manifold as a single piecerather than as two separate pieces. Since the bowl and filter cartridgeare removed together, the filter cartridge need not be removed from thebowl. Thus, a space substantially equal to the length of the filtrationcartridge and the bowl together need not be provided to remove thefilter cartridge. Only a space as long as substantially the length ofthe bowl need not be provided. This permits one to install a filtrationcartridge of this invention within a smaller space as compared to thespace required with present filtration modules. In addition, since thefiltration cartridge is removed with the bowl, it need not be handled bya worker either by hand or with a hand tool. This substantially reducesthe possibility of contacting fluid within the bowl with a worker. Thebowl optionally can contain a drain for removing fluid before removal.

Referring to FIG. 1, a filtration module 10 comprises a manifold 12, abowl 14 and a filter cartridge 16. A threaded ring 18 is positioned onthe outside surface 20 of bowl 14 and is retained thereon by bead 22which extends around the circumference of the bowl 14 and lip 24. Bycontrolling the size and flexibility of bead 22, the ring 18 can beslipped over the bead 18 to position the ring 18 or the bead 22 can beformed on the bowl 14 after the ring 18 is positioned as shown.

The ring 18 is substantially fixed in its position relative to the bowl14, i.e., it cannot move any substantial distance along the length ofthe bowl 14. When its threads 26 and 28 are drawn together, the ring 18carries or drives the cartridge 16 into affirmative contact withmanifold 12 to effect sealing with O-rings 11 and 13. Conversely, whenthe ring 18 is rotated so as to drive the threads 26 and 28 apart, thecartridge 16 is positively carried or driven away from the manifold 12.

The cartridge 16 is connected to bowl 14 by flanges 15 on key 30 whichmate with slots 32 in collar 34. The collar 34 is threaded into bowl 14by threads 36. The collar 34 extends about the entire innercircumference of bowl 14. Alternatively, the bowl and collar can beformed of one piece in the shape of bowl 14 and the collar 34 such as bymolding. The key 30 fits onto two flat surfaces 38 and 40 positioned onthe outside surface of fluid passageway 42 of cartridge 16. Fluidpassageway 42 includes sealing O-rings 11 and 13 and can function as aninlet or outlet for cartridge 16. When the fluid passageway functions anan inlet, fluid is introduced into inlet 44 of manifold 12. When thefluid passageway 42 functions as an outlet, fluid is introduced throughinlet 46 of manifold 12. Since flanges 15 do not extend about the entirecircumference of the key 30, fluid is capable of by-passing the key 30to flow into the manifold 12. The structure of the key 30 will be morefully described with reference to FIG. 2. The structure of the collar 34will be more fully described with reference to FIG. 3.

Referring to FIG. 2, the fluid passageway 42 of cartridge 16 is modifiedto form two flat surfaces 38 and 40 (not shown, see FIG. 1) positionedsubstantially parallel to each other. The flat surfaces 38 and 40 fitwith flat surfaces 39 on key 30. The key 30 includes two flexible legs33 which can be opened so that flat surfaces 38 and 40 mate with flatsurfaces 39. By being so-shaped, the key 30 is fit around fluidpassageway 42 to provide a strong connection between the key 34 and thefluid passageway 42 while avoiding significant blockage of thepassageway 42. The key 30 also can include optional vertical extensions35. The filter cartridge 16 includes a top cap 19, a bottom cap 21, afilter 23 and a porous housing 25. The caps 19 and 21 are sealed to theends of the filter 23 to prevent admixture of fluid feed with permeate.The structure of the filter cartridge 16 assures that fluid entering thefilter cartridge 16 passes through the filter 23 prior to exiting thefilter cartridge 16. The filter 23 can be a depth filter, a pleatedfilter or the like. The optional vertical extensions 35 fit into thedetents 45 shown in FIG. 3.

Referring to FIG. 3, the collar 34 includes two cutouts 41 and twovertical extensions 43. Each vertical extension 43 includes a slot 32(one not shown). The slots 32 fit with and accommodate flanges 15. Theangle subtended by slots 32 depend upon the flexibility of the materialused to make key 30 and collar 34. The slots 32 subtend an angle of atleast about 15 degrees, preferably between about 30 and about 45 degreeswhen the key 30 and collar 34 are made of relatively flexible polymer ifperfluoro(alkylvinyl ether) (PFA). When the key 30 and collar 34 aremade of relatively rigid material such as high density polypropylene,these angles can be about one-half that for PFA. This size angle withthese exemplary materials provides a desired contact surface between theflanges 15 and the slots 32 so that the key 30 is not separated from thecollar 34 during use of the filtration module 10. The collar 34 includesdetents 45 which fit with and accommodate vertical extension 35 s withincollar 34. The collar 34 also includes optional vertical slots 17 whichpermit drainage of fluid between the collar 34 and the manifold 12.

Referring to FIG. 4, a bowl and collar construction of this invention isshown. The collar 34 is threaded into the bowl 14. The collar and bowl14 can be molded as one piece. The bowl 14 includes a plurality of stops50 which support a locking ring (not shown). The bowl 14 includes adrain 17 that can be open or closed. The drain 17 is closed duringfiltration.

Referring to FIG. 5, a construction is shown which permits rotation ofthe key 30 so that flanges 15 fit into slots 32. The pronged C shapedtool 52 has prongs 54 which fit into holes 56. The tool 52 permitsavoidance of hand contact with a used cartridge 16.

Referring to FIG. 6, a construction is shown which protects the interiorof a filter cartridge prior to use and which permits avoidance of handcontact with the filter cartridge 16. The cap 52 fits over fluidpassageway 42 to seal the interior of cartridge 16 from the atmosphere.The cap 57 is molded with a handle 58 which permits insertion andremoval of the cap onto or from the fluid passageway 42. The handle 58permits rotation of the flanges 15 into the slots 32 of collar 34 byhand. After the flanges are so-positioned, cap 57 can be removed fromfluid passageway 42 by pulling on handle 58.

Referring to FIGS. 7 and 8, an alternative construction is shown forjoining a filter cartridge to a bowl. The key 60 is provided with twoprongs 62 which are slideably connected to fluid passageway 42 incontact with two flat surfaces 64 which are substantially parallel toeach other in the same manner described above with reference to FIG. 1.As shown in FIG. 8, the hook-shaped prongs 66 fit over lip 68 of bowl14. The key 60 also is provided with levers 67 which are pivoted so thathand pressure on the levers 67 permits movement of prongs 66 intocontact with or away from contact with the bowl 14.

While the key of this invention has been described with reference to twoopposing attachment elements (flanges or prongs), it is to be understoodthat the key can be provided with more than two attachment elements. Atleast two attachment elements are required in order to prevent thecartridge from pivoting with respect to the bowl.

Since the key of this invention is removable from the cartridge, thecartridge of this invention can be utilized with the bowl of thisinvention described above or with a conventionally sized bowl. Theremovable key permits the cartridge without the key to be inserted intoa conventional bowl having no slots on its inner surface otherwise theflanges on the key would render the footprint of the overall cartridgeand key to be larger than the conventional bowl diameter. This, in turn,allows for a reduction in required inventory of cartridges needed toaccommodate a conventional bowl and the bowl of this invention.

In use, the levers 67 of the cartridge of FIG. 7 are subject to handpressure thereby to move the prongs 66 away from the flat surface 64.The cartridge is dropped into the bowl, hand pressure on the levers 67is released and the prongs 66 thereby are secured to the top lip of thebowl to secure the key 60 to the bowl.

The embodiment of FIG. 2 is inserted into the collar of FIG. 3 byaligning the flanges 15 with cutouts 41. The key 30 is then rotated sothat flanges 15 fit into slots 32 thereby securing the cartridge 16 tothe collar 34.

In one aspect of this invention, the key is provided with an outsidesurface configuration which mates with an inside surface configurationof the collar attached to the bowl in order to center the filtercartridge to which it is attached within the bowl. Centering thecartridge within the bowl allows for a smooth mating of the key andcollar when the key is rotated into the collar. The outside surfaceconfiguration of the key includes a small groove. While this outsidesurface configuration is not required in this invention, in its absence,the key will slide from side to side within the collar therebyincreasing difficulty of engaging the key and collar.

Referring to FIGS. 9 and 10, the key 70 includes a groove 72 on each keyleg 74 and 76 which mates with a surface 78 of collar 80. While FIGS. 9and 10 include bosses 82, they are not necessary to the groove's 72function. The purpose of the bosses 82 are described below.

In another aspect of this invention, the collar of this invention isprovided with slots which extend through the thickness of the collar.The slots mate with bosses on the key to provide an improved fit betweenthe collar and the key. The bosses are configured to cause mating slotson the collar to expand outwardly when the key is rotated into positionuntil the bosses fit into the open slots. At the point of fitting, theslots contract toward each other and thus overlap renders it moredifficult for the key to become detached from the collar during use.

Referring to FIGS. 11, 12, and 13, the collar 84 includes two opposingslots 86 and 88 into which fit the bosses 82 when the key 90 is rotatedinto position into collar 84. Expansion of the slots away from eachother is caused by contacting the bosses 82 with the inside surfaces ofthe collar 84. The distance between the outside surfaces of the bosses82 is slightly larger than the distance between opposing inside surfacesof the collar 84.

1. A filter cartridge which comprises: an elongated filter medium havinga first end and a second end, a first sealing plate sealed to said firstend, a second sealing plate sealed to said second end, a fluidpassageway sealed to said first sealing plate to provide fluidcommunication to an open interior within said filter medium, said fluidpassageway having an outside surface including two substantiallyparallel flat surface and a fluid porous housing surrounding an outsidesurface of said filter medium.
 2. The filter cartridge of claim 1wherein said filter medium is a depth filter.
 3. The filter cartridge ofclaim 1 wherein said filter medium is a pleated filter.
 4. A filtrationmodule which comprises: a manifold, a filter cartridge and a bowl whichhouses the filter cartridge, and means for locking said bowl to saidmanifold, a key secured to two substantially parallel surfaces on anouter surface of a fluid passageway formed with the filter cartridge,said key having at least two attachment elements attached to said bowl,said filtration cartridge and bowl being in fluid communication withsaid manifold in a manner which prevents mixing of a fluid feed to saidfiltration cartridge with a permeate removed from said filtrationcartridge.
 5. The filtration module of claim 4 wherein said key isattached to said bowl by prongs extending from said key which fit over alip of said bowl.
 6. The filtration module of claim 4 wherein said keyis attached to said bowl by flanges extending from said key which fitinto slots on a collar, said collar being directly attached to an openend of said bowl.
 7. The filtration module of claim 6 wherein said bowland said collar comprises a unitary construction.
 8. The filtrationmodule of any one of claims 4, 5, 6 and 7 which includes an inlet forfluid feed to said bowl and an outlet for permeate from said filtercartridge.
 9. The filtration module of any one of claims 4, 5, 6 and 7which includes an inlet for fluid feed to said filter cartridge and anoutlet for permeate from said bowl.
 10. The filtration module of any oneof claims 4, 5, 6 or 7 wherein said key includes at least one verticalextension, each of said at least one vertical extension being fit into avertical slot in said collar.
 11. The method for reducing a requiredinventory of filter cartridges which fit with both a first set of filterbowl being free of a slot on an inner surface of said first set offilter bowls and a second set of filter bowl having at least two slotson a second inner surface of said second set of filter bowls whichcomprises: providing said second set of filter bowls with a key havingat least two flanges which fit into said at least two slots, said keybeing removable from said second set of filter bowls.
 12. The filtrationmodule of any one of claims 4, 5, 6 or 7 wherein said key includes atleast two flanges and each of said flanges has a boss on an outsidesurface of each of said flanges.
 13. The filtration module of any one ofclaims 4, 5, 6 or 7 wherein said key includes at least two flanges andeach of said flanges includes a groove on a lower surface of each ofsaid flanges, said groove shaped to mate with an inner surface of acollar attached to said bowl.
 14. The filtration module of any one ofclaim 8 wherein said key includes at least two flanges and each of saidflanges includes a boss on an outside surface of each of said flanges.15. The filtration module of any one of claim 9 wherein said keyincludes at least two flanges and each of said flanges includes a bosson an outside surface of each of said flanges.
 16. A sealing plate for afilter cartridge comprising: a plate having a fluid passageway extendingthrough said plate, said fluid passageway having an outside surfaceincluding two substantially parallel flat surfaces.